Biotinylated thyroxine

Abstract

A means for conveniently and accurately measuring thyroxine or thyronine present in the blood or the like is provided: a compound represented by general formula (I) below: wherein L represents a linear or branched-chain linker having 5 to 50 total atoms; X represents one or more thyroxines, thyronines, or residues of derivatives thereof, bound to the main chain and/or side chain of the linker represented by L, a conjugate in the form of the above compound bonded to an avidin protein, and an aqueous dispersion including a microparticles the surface of which is modified with the above conjugate.

1 . A compound represented by general formula (I) below: 
     
       
         
         
             
             
         
       
     
     wherein L represents a linear or branched-chain linker having 5 to 50 total atoms; X represents one or more thyroxines, thyronines, or residues of derivatives of thyroxine or thyronine, bound to the main chain and/or side chain of the linker represented by L. 
   
   
       2 . The compound according to  claim 1 , in which the linker represented by L comprises at least one chain-like structure selected from the group consisting of an alkyl chain, a polyethylene glycol chain, and a peptide chain. 
   
   
       3 . The compound according to  claim 2 , in which L comprises one or more bonds selected from the group consisting of an amide bond, an ester bond, and a carbamate bond in addition to an alkyl chain and/or a polyethylene glycol chain. 
   
   
       4 . The compound according to  claim 1 , in which the main chain of the linker represented by L consists of 15 to 20 atoms. 
   
   
       5 . The compound according to  claim 1 , in which the main chain of the linker represented by L is 25 to 30 Angstroms in total length. 
   
   
       6 . The compound according to  claim 1 , wherein the residue is a residue obtained by removing the hydrogen atom from a carboxyl group of thyroxine, thyronine, or a derivative of thyroxine or thyronine, or a residue obtained by removing one of the hydrogen atoms in the amino group of thyroxine or thyronine. 
   
   
       7 . The compound according to  claim 1 , wherein the derivative is a carboxylic acid ester derivative or an amino group-modified derivative. 
   
   
       8 . The compound according to  claim 1 , having an interaction with an avidin protein represented by a Kd value of 1×10 −13  or lower. 
   
   
       9 . A compound represented by the following formula: 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents hydrogen atom or iodine atom. 
   
   
       10 . A conjugate in the form of the compound represented by general formula (I) set forth in  claim 1  bonded to an avidin protein. 
   
   
       11 . The conjugate according to  claim 10 , wherein the avidin protein is avidin, streptavidin, or neutra-avidin. 
   
   
       12 . An aqueous dispersion comprising a microparticle the surface of which is hydrophilically treated, the surface of said microparticle being modified with the conjugate set forth in  claim 10 . 
   
   
       13 . The aqueous dispersion according to  claim 12 , wherein the microparticle is a carboxy hydrophilically-treated polystyrene bead. 
   
   
       14 . The aqueous dispersion according to  claim 13 , wherein the avidin protein moiety of the conjugate is contained in a hydration layer formed on the surface of the carboxy hydrophilically-treated polystyrene bead. 
   
   
       15 . The aqueous dispersion according to  claim 12  employed for a measurement of thyroxine or thyronine. 
   
   
       16 . A method for measuring thyroxine or thyronine using the aqueous dispersion set forth in  claim 12 .